Experimental Investigations in Low-Noise Trailing Edge Design.

TLDR

The study aims to develop scaling laws for brush‑type trailing‑edge extensions as add‑on solutions for modern aircraft. Experiments combined acoustic and aerodynamic measurements on a zero‑lift plate in DLR's open‑jet wind tunnel, using directional microphones, to identify bluntness‑noise suppression and turbulent boundary‑layer noise reduction as key mechanisms. The parametric study demonstrates that brush‑type trailing‑edge extensions can reduce source noise by more than 10 dB, depending on configuration.

Abstract

Within a parametric study on brush-type trailing-edge extensions, the noise reduction potential of several design concepts was determined. The obtained database represents the first phase of an ongoing project with the long-term objective to develop scaling laws for a future application of such devices as add-on solutions for today's aircraft components. The experiments comprised both acoustic and aerodynamic measurements on a zero-lift generic plate model (Re = 2.1 x 10 6 to 7.9 × 10 6 ) in DLR's open jet Aeroacoustic Wind Tunnel Braunschweig. Noise data were taken by means of a directional microphone system. Measurement results indicate a significant source noise reduction potential in excess of 10 dB, depending on the configuration. Two relevant noise reduction mechanisms were identified: 1) the suppression of narrowband bluntness noise, as well as 2) the reduction of broadband turbulent boundary-layer trailing-edge noise.